Exactly a year to the moment that a pair of shooters unleashed a terrorist attack on San Bernardino, a bell rang 14 times Friday at the city's Inland Regional Centre in honour of the people who died there.

“We will never forget that day or the victims of this senseless act of violence. We strive to move forward and search for the good that is in us all,” said Lavinia Johnson, the centre's executive director.

During the ceremony outside the centre, employees of nearby businesses who sheltered people during the chaos were also thanked by Keith Nelson, the centre's chairman.

In all, 14 people were killed and 22 wounded.

Among those attending the ceremony was Zen Martinsen, 56, a clerical supervisor for San Bernardino County. While she didn't know the victims who had gathered at the centre for a county event that day, she said all county employees are like family.

“This affects everybody and I think it's just really important that terrorism doesn't win,” she said.

“We can't let it win.”

The ceremony was just one of a series of events scheduled in the hardscrabble city of 216,000 people east of Los Angeles to mark the anniversary of the Dec 2, 2015, attack by husband-and-wife assailants on a holiday luncheon for county health employees.

Investigators say the attackers were inspired by the militant Islamic State group.

Earlier, cyclists conducted a 14-kilometres bike ride one mile for each person who was killed.

Friday evening some 500 people gathered at California State University, San Bernardino's, Caussoulis Arena for a sombre memorial for the victims.

Among the numerous speakers, which included the city's police chief and mayor, was Julie Swann-Paez, who was gravely wounded by the shooters.

Swann-Paez, whose pelvis was shattered by a bullet, spoke warmly, and sometimes humorously of each of those killed. Still, she choked up from time to time, while some in the audience wept.

Most of those killed in the attack by county health inspector Syed Rizwan Farook, and Farook's Pakistani wife Tashfeen Malik, were Farook's colleagues.

While the city of San Bernardino has been grappling with a spike in homicides this year, community residents have worked hard to prevent a hate-filled backlash to the terror attack.

Clergy have formed an interfaith alliance, victims' families have encouraged tolerance and Muslim residents undertook a campaign to educate neighbours about Islam.

Since the attack, San Bernardino police Sgt. Emil Kokesh said he has also been reminded of the need to stay fit.

Kokesh arrived at the scene of the onslaught minutes after the shooting and was there for more than a day.

He said he was sore for two weeks, which prompted him to take up cycling to get in shape with some fellow officers.

That led to the memorial bike ride.

“On that day, it pushed a lot of us to our limits physically, mentally, and emotionally,” he said.

Now, Kokesh said he often reminds his fellow officers: “You may work in an office, you may do investigations, and not do much field work anymore, but you are going to be the ones who respond to something like this, so stay fit, stay prepared.”

The Inland Regional Centre provides case management services for people with developmental disabilities, cerebral palsy, epilepsy and autism.

The building where the attack occurred is still closed and is undergoing remodelling. It is expected to reopen in early 2017, and a memorial to the victims is planned, Kevin Urtz, the centre's associate executive director said.